Laser scanning has been used in many fields. Laser printers, bar code readers and optical tape data recorders are examples of laser scanning applications. Laser scanning is also important in the semiconductor industry. It has been used in scanning laser microscopes, semiconductor processing, and in laser pattern generators which produce reticles for wafer steppers.
By far the most widely used laser scanning device is the rotating polygonal mirror which is found in almost every laser printer. The optical system in a typical laser printer involves a laser source, an acousto-optic modulator, a beam expander, a rotating polygonal mirror and a cylindrical focussing lens. The laser beam is switched at very high speed by the acousto optics modulator and then expanded to a desirable diameter. The expanded laser beam is then scanned and focussed, producing a scan line of tens of centimetres in length with up to thousands of resolvable spots. The spot size for a typical laser printer is in the order of tens of microns (1 micron =0.001 mm).
Two articles disclose integrated circuit processes which have relevance to this field of technology.